This invention relates to polyurethane latexes, processes for preparing them, polymers prepared therewith, and substrates coated therewith. This invention particularly relates to coating substrates having polar surfaces with polyurethane latexes.
Latex polymers are known to be useful in many applications such as paints, sealants, and films. Polyurethane latexes are less widely used due to inherent difficulties in preparing stable aqueous polyurethane latexes. For example, polyurethane formulation components, such as polyisocyanates can be reactive with water. Polyurethane prepolymers useful for forming latexes are often not low viscosity liquids at ambient conditions. These and other properties can cause polyurethane latexes to be unstable, that is to form a dispersion which separates from the continuous aqueous phase of the latex, which is often not desirable in an industrial venue.
Recently, there have been several advances in the art of preparing stable, organic solvent free, polyurethane latexes. For example, U.S. application Ser. No. 09/039,976 filed Mar. 16, 1998, the teachings of which published as WO 98/41554 on Sep. 24, 1998, discloses preparing such polyurethane latexes. U.S. application Ser No. 09/039,978 filed Mar. 16, 1998, now abandoned in favor of its divisional application, U.S. application Ser. No. 09/551,400 filed Apr. 19, 2000, discloses preparing carpets using polyurethane latexes. As these latexes become more available and widely used, it will be desirable to improve their performance, particularly in regard to physical properties.
It would be desirable in the art of coating substrates with polyurethane latexes to be able to coat substrates having polar surfaces with a polyurethane latex having good adhesion thereon. It would be particularly desirable if the polyurethane latex which has good adhesion on polar surfaces was an aqueous, organic solvent free, polyurethane latex.